ABSTRACT ? FLOW CYTOMETRY SHARED RESOURCE The Flow Cytometry Shared Resource offers Cancer Center members multi-parametric evaluation and high- speed enrichment of phenotypically distinct cell populations. The Core provides full-service high-speed cell sorting performed by expert operators, utilizing two BD Aria instruments in biosafety enclosures. For analytical cytometry, investigators have a choice of either full-service analysis by Core staff or receiving training and then independently using one of six analytical flow cytometers. Those analytical cytometers, available 24/7 to trained users, include two BD Fortessas, the newer of which is a 5-laser, 18-color instrument, and an ImageStreamX MkII imaging flow cytometer with four lasers and 12 imaging channels. Many of the Core's cytometers have autoloaders, enabling larger-scale experiments. Analysis software is available in the Core or via the Institutional site license. This broadly used Core is managed by the CC and receives support from the Institute for instrumentation purchase and maintenance. In the last funding period, three major technology platforms were acquired, and imaging flow cytometry was launched as a new service. The Core Director, Mr. Altman, and staff have combined experience of more than 30 years in NCI-designated Cancer Center Flow Cytometry Cores, and they provide comprehensive technical guidance at any stage of a project, from experimental design through manuscript preparation. The Flow Cytometry Core is broadly used, as in the last 5 years, it was used by 46 Cancer Center labs representing all three programs, and the Core contributed to at least 75 cancer-related publications.